import java.util.Stack;

/**
 * @Author：KoVaVo
 * @Version：1.0.0
 * @Description：
 */
public class test {

    public static void main(String[] args) {
        StringBuilder sb = new StringBuilder();
        for (char c= 'a'; c <= 'f';c++){
            sb.append(c);
        }
        System.out.println(sb.toString());


        Stack<String> stack = new Stack<>();
        boolean add = stack.add("add");
        stack.push("push");
        int a  = Integer.MIN_VALUE;
    }

}
